There are anecdotal stories of people entering higher states of consciousness during near death experiences, extremely deep meditation, holotropic breathing exercises, etc.
Really creative people describe their most proud acts of creation as if the idea came from somewhere else. As if the concept arose independently and they tried their best to relay it into the real world.
As for the people on psychedelic drugs, they usually speak of the higher state of consciousness as being more real than the real world... which would make sense if our usual consciousness was a subset of something bigger.
I actually don't believe that consciousness stops at cells or solar systems :). I am a panpsychist which holds the view that everything in our universe is made up of consciousness (just not the super intelligent type that we typically associate with the word).
People usually get hung up on the idea... "how can you consider this rock to be conscious". Well within this rock there are protons, neutrons, electrons, atoms, molecules, etc, that all "know" how to do their thing to form a rock. If things weren't conscious then nothing in our universe would have a shape. I believe that higher states of consciousness arise from simpler lower states.